Ceramic component blocks are typically piezo stacks which are used in the production of piezo actuators.
A piezo actuator generally consists of a number of piezoceramic plates. A piezoceramic is a material which expands because of the piezoelectric effect when a voltage is applied to it. Such piezoceramics form the basis for the piezo actuators, which implement a movement path of a few micrometers when a voltage is applied. The piezoceramic has electrical dipole moments which each exhibit a preferred direction within Weiss domains which are delimited from one another. In an unpolarized basic state of the piezoceramic the preferred directions of the individual Weiss domains have no arrangement so that to the outside there is no macroscopic electrical polarization of the piezoceramic present.
To make the piezoelectric effect usable for piezo actuators, the piezoceramic must be polarized by the alignment of the electrical dipole moments, after which the electric dipole moments in all Weiss domains do not deviate or deviate only slightly from a preferred direction specified by the polarization axis. The piezoceramics are used for example as basic bodies of piezo actuators, which are used in such areas as automotive technology, for example as electromagnetic converters in common rail injection systems for internal combustion engines.
The individual piezoceramics described above are provided on both sides with metallic electrodes or internal electrodes. If a voltage is applied to these internal electrodes, the piezoceramic reacts with a lattice distortion which leads along the main axis to the usable length extension already described above. Since however this only amounts to 2 thousandth of the layer density along the main axis, to achieve the desired absolute length extension a correspondingly greater layer thickness of active piezoceramics must be provided. With increasing layer thicknesses of the individual piezoceramic layers within a piezo actuator however, the voltage required to make the piezo actuator respond also increases. To keep this within manageable limits, the thicknesses of individual piezo layers with multilayer actuators usually lies between 20 μm and 200 μm. Therefore, for a desired length expansion, a piezo actuator must have a corresponding number of individual ceramic layers.
It is known to the inventor that piezo stacks can be manufactured for example by arranging piezo ceramic green films in a stack alternately with internal electrode material.
The inventor also knows from internal sources that the piezo stack can be manufactured in multi images by stacking a plurality of “green” unsintered ceramic films or piezo ceramic green films or piezo layers onto each other and subsequently compressing them. This stack is subsequently to be separated or to be split into a plurality of individual components.
Wire saws are known from semiconductor technology for separating or splitting the individual components. To this end FIGS. 1A and 1B show a schematic longitudinal cross section or a schematic transverse cross section of a conventional wire saw DS. With a conventional wire saw DS of this type a plurality of wafers are cut from a silicon monocrystal using a wire D or by means of parallel wire sections DA1-DA13 formed therefrom. To this end the wire D is routed several times in parallel via deflecting rollers U1-U3 in order to produce a wire harp DH or wire lattice. However the distances or the respective offset VS between the individual wire sections DA1-DA13 is restricted to a narrow measurement of a few millimeters, since otherwise the wire D would jump out of its guide or the wear on the wire D as a result of mechanical stress would be too great. This distance of a few millimeters is however too small for the cutting width of the piezo stack needed, so that the wire saws known from semiconductor technology cannot be used for separation of ceramic components, such a piezo stacks.
Such a wire saw is known for example from publication U.S. Pat. No. 4,494,523. With this wire saw in the actual saw area of the wire is guided as a type of harp over three deflection rollers arranged in a triangle having at least the diameter of the workpiece, of which one is driven. The workpiece is initially located inside the prism-type arrangement and during the separation process is pushed from below against the horizontally tensioned area of the moving wire.